Q. I'm living in Shenzhen, People's Republic of China. I live on the 9th floor of our 34 floor apartment building, and just had to have our external air conditioning serviced. I was alarmed and amazed as our air conditioning technician tied a rope around himself, and then went out the window to the external air conditioning unit to give it a dose of freon (as I held the rope!). My gf asked, what do they do in the USA?

A. In the USA buildings have central Air-Conditioning and the equipment is usually located on the roof of the building.

Q. The air conditioning in our house went out over night & last time it happened (about a month ago) we changed the filter & it worked again just fine. So, we changed the air filter agian, but this time no luck. it's not sucking in air where the filters go, any suggustions -- besides calling someone over to repair?

A. Either your fan/blower isn't working, or for some reason it isn't trying to run. Check breakers, and fuses. thermostat setting.

Q. I just got the ducts in my house cleaned out to get rid of pet dander and help me breathe better. The air conditioning is running great now and seems cleaner to breathe in. The only problem is that there is a loud humming noise coming from the big vent on the wall. It only comes from this big vent, and does not resonate from any of the vents on the ground. The big vent is not the original big vent; my contractor replaced it after the ducts were cleaned because the old big vent was dirty. My contractor says the noise is a result of the air running so openly now, but I'm having a hard time buying that. I think it is the replacement vent vibrating when the air pushes through it. Any thoughts? I'm pretty sure he threw away the old big vent.

A. Call him back and tell him your not satisfied.Lining the duct with duct insulation should help.I think your right about the vibration.

Q. The filter is completely frozen over with ice we cant even remove it.

A. Shut the AC off and let it defrost. Thats usually caused because the filter clogged from not being changed or cleaned. When the filter clogs, air can't circulate and the coils freeze up.

Q. I live in an upstairs condo. I have a small window air conditioning unit. I was going to install it on a shelf outside the window, but my guys said it is fine sitting on the window ledge backed up to the screen of the window and lowering the window down on top of it, as it has exhaust and intake. Any air conditioning experts out there who could tell me if this is a less efficient way for it to run, or is it all right?

A. Unless things have changed, the screen is approx. 3 to 4 inches from window sash ( the glass) the unit is about 14-16 inches deep. they r designed to sit flush to the sash with the upper arm( brace) touching the bottom of the sash u raised to put the unit in.and the slides on the side of the unit slide over to cover the gaps. i think u would be wise to read the instructions and follow them.

Q. I am trying to find out how the sanitation process works and if it causes chemical smells in the house? I'm starting to use the air conditioner in our new apartment and everytime it comes on I end up with a headache and the air smells musty. I have been informed by the air conditioning company that it needs to be cleaned and sanitized, I am concerned about the chemicals they will be using as I am senstive to chemicals. Anybody have this done before and know how it effected your home?

A. I have asthma,allergic to dust. We had our furnace ducts/pipes cleaned out ! I had no problems. The ho user is 6o years old. I do not think the pipes were ever cleaned. You should have no problem if it is a repitule company

Q. What is the capacity of air conditioning unit to be use when you install at specific area and equipment loads availabilities?

A. You need more info here. The answer to this question is "install one with a capacity sufficient to control the load." To determine the capacity, add up the loads, multiply by the diversity factor, and you're done.

Q. I just moved into a new home that had never had the ducts cleaned. The house is a ranch with gas forced air heat on one zone with about 9 vents. I found this company on a coupon for $45 which included unlimited vents and a couple access holes. When the company began their work they found mold and the price skyrocketed from $45 to $1400. Does this sound like a screw job or is that price accurate for mold removal and duct cleaning?

A. Mold removal/remediation is entirely different from air duct cleaning. However, it is not uncommon to find mold in your air ducts. That is why we recommend the Electro Breeze Duct Mount UV kit at http://www.allergy-relief-air-purifier.com/air-conditioning-filters.html. This unit will eliminate mold and bacteria from your indoor air and keep your air conditioning coils clean from mold. You must consider that to remove the mold from your air ducts, the air duct cleaning company is entering into a potentially dangerous situation for their employees. This requires expensive equipment and a person with the skills to do the remediation properly. Now that they have knocked the mold loose, you will need the high efficiency filtration and ultra-violet light of the Electro Breeze DMUV kit to kill and capture the mold spores in your indoor air. I hope this helps.